In recent years, an active study has been made of semiconductor nanoparticles capable of controlling the fluorescent wavelength due to the different particle size. The semiconductor nanoparticles have been studied and utilized as fluorescent markers labeled inside or outside of a living organism, since they have controllability of the fluorescent wavelength, high light fastness and high surface modification freedom (see for example, Patent Documents 1 through 3 described later).
Particularly in recent years, there has been actively made a fundamental medical study, in which analysis of reaction mechanism of living molecules within living cells is shifted from qualitative assay in a bulk living organism analysis to kinetic analysis at molecule level, or a study on bioimaging, in which biological action of viruses or bacteria causing diseases, or biological action of medicines is analyzed. Particularly, as is represented by molecular imaging, information (dynamics from DNA transfer mRNA to protein formation, cell apoptosis dynamics, etc.) regarding a biological substance, which has not been obtained hitherto, is obtained by conjugating one molecule of a biological substance to be detected (nucleuses within cells, endoplasmic reticulum, Golgi body, proteins, DNA, RNA) with one or several molecules of a fluorescent labeling agent, irradiating the conjugate with an excitation light, and detecting the emission light. When target substances within living organisms such as living cells or small animals are traced, qualitatively or quantitatively analyzed, it is desired that the plural target substances can be simultaneously analyzed. Trace due to simultaneous marking is essential in order to analyze mechanisms such as a biological mechanism in which plural molecules within cells participate, a developing mechanism of viruses, and endocytosis.
However, organic fluorescent dyes or fluorescent proteins hitherto used as markers are small in Stokes shift which is the difference in wavelength between excitation light and emission light and the different organic fluorescent dyes are necessary to be irradiated with an excitation light suitable for each of the organic fluorescent dyes Therefore, when simultaneous multi (many or many kinds) analysis is carried out, excitation light sources equal to the number of markers are required, resulting in complexity and cost increase of an analysis device, an excitation-fluorescent light separation filter, which is necessary on account of small stokes shift, inhibits fluorescence from other markers in the plural markers, and plural excitation lights result in fluorescence noise. Thus, multi analysis has been difficult (see for example, Patent Document 4 described later).
With respect to kinetic analysis of molecules, which has been actively studied in fundamental medical areas, it is pointed out that emission intensity to be detected per one sample is poor and its discrimination accuracy in multi analysis is low. Accordingly, further improvement in discrimination accuracy has been desired.
In order to solve the above problems regarding the multi analysis, it is necessary to manufacture semiconductor quantum size particles with high accuracy and in a number necessary to multi analysis, the particles exhibiting quantum effects that are different in emission wavelength according to the different particle size. However, this manufacture itself is difficult.    Patent Document 1; Japanese Patent O.P.I. Publication No. 2003-329686    Patent Document 2: Japanese Patent O.P.I. Publication No. 2005-172429    Patent Document 3: Japanese Translation of PCT International Application Publication No. 2003-524147    Patent Document 4: Japanese Patent O.P.I. Publication No. 2003-287498